This invention relates to a sealing arrangement and more particularly but not exclusively to a sealing assembly for sealing a door in a aircraft fuselage, such as a helicopter fuselage, relative to a door frame or coaming.
Particular problems are encountered in providing weatherproof sealing arrangements for doors of helicopter fuselages. First, vibration, particularly in flight, assists water migration between sealed faces. Second, helicopter doors are often made of materials which are able to flex under load, such as resin fibre glass composite materials, and such flexing can allow water to migrate past door seals. Third whereas it is known to provide a weathertight door sealing arrangement by the use of pressurised air to inflate a pressurised seal, such pneumatics are unavailable in a helicopter. Fourth, helicopter cabins tend to be un-pressurised and so again a pressure differential cannot advantageously be used to achieve more effective sealing. Fifth, aerodynamic suction on the door tends to be experienced in flight, resulting in doors being pulled outwardly, again compromising any door sealing arrangement.
Door sealing arrangements for particular use in a helicopter are known which include a substantially xe2x80x9cDxe2x80x9d shaped seal. Referring to FIG. 1, in such a known sealing arrangement, a xe2x80x9cDxe2x80x9d shaped seal 12 is provided with a flat surface 13 thereof attached to a helicopter door 10, with a rounded seal part 14 received in a two sided recess 15 in the door coaming 16, when the door 10 is closed. In such an arrangement a single contact area is thus provided between the rounded seal part 14 and the surface of the recess 15 and the seal operates purely to try and prevent the ingress of water past the mating surfaces, there being nothing other than the resilience of the seal 12 to prevent the seal 12 separating from the coaming 16 in response to vibration and aerodynamic suction loads, and door 10 flexing.
According to one aspect of the invention we provide a sealing arrangement between an opening leaf and a frame, one of the frame and leaf providing an elongate recess, and the other of the leaf and frame carrying an elongate seal which, when the leaf is closed with respect to the frame, is received in the recess, characterised in that the elongate seal includes a plurality of axially extending outwardly projecting formations, and an internal hollow, the recess and the seal being configured such that as the leaf is closed and the seal is received in the recess, a first of the axially extending outwardly projecting formations of the seal engages with a respective first part of an inside surface of the recess and as the leaf is continued to be closed, the seal becomes deformed in a manner to cause the or at least one of the other axially extending outwardly projecting formations to be urged into sealing engagement with as second part of the inside surface of the recess.
By virtue of the invention, an improved more efficient seal particularly but not exclusively for use for sealing a leaf which is a door of an aircraft, with respect to a frame such as a coaming, is provided.
Preferably the seal is of a generally tubular construction having an internal axially extending hollow defined by a tube wall, the hollow in cross section, generally conforming to the external configuration of the seal. The tube wall may be shaped to conform generally to the external configuration of the seal, the tube wall and hence the configuration of the internal hollow deforming as the leaf is closed with respect to the frame.
In a preferred arrangement the seal includes at least three axially extending outwardly projecting formations each arranged to engage with a respective part of the inside surface of the recess as the leaf is closed with respect to the frame, the first axially extending formation being located intermediate a pair of other axially extending formations, and the first axially extending outwardly extending formation engaging with the first part of the inside surface of the recess thus to cause deformation of the seal as the leaf is continued to be closed, such as to urge the pair of other axially extending outwardly extending formations mutually away from one another into sealing engagement with respective parts of the inside surface of the recess.
The seal may have an axially extending generally plain surface part by means of which the seal is attached to the leaf or the frame, with the first outwardly projecting formation extending generally normally to the plain surface part, and the other outwardly projecting formations being located either side of the first formation, and extending outwardly along a line which is generally parallel with the generally plain surface part.
Conveniently, the elongate recess of one of the leaf and frame, is generally channel shaped and has a mouth which, when the leaf is closed in the frame, faces the other of the frame and the leaf respectively, with the outwardly projecting formations of the seal each being in sealing engagement with the inside surface of the channel when the leaf is closed with respect to the frame.
The first inside surface part of the channel with which the first axially extending outwardly projecting formation engages as the leaf is closed with respect to the frame, may thus be at a base of the channel, the other axially extending outwardly projecting formations being urged as the seal deforms, into sealing engagement with respective inside surface parts which are provided at sides of the channel.
By virtue of the provision of axially extending outwardly projecting formations which are urged into sealing engagement with the inside surface of the recess, when the leaf is closed with respect to the frame, axial voids are provided between the outwardly projecting formations of the seal and the inside surface of the recess, which voids may be used for drainage of water from between the outwardly projecting formations and the inside surface of the recess.
Where at least three outwardly projecting formations are provided, at least two axial voids may be provided between adjacent pairs of the formations.
Any water passing an outermost of the outwardly projecting formations of the seal may be drained from a void between the outermost and next inner formation, via the internal hollow of the seal, there being a plurality of openings into the internal hollow from the void through which water to be drained may pass.
In one construction, the frame and the leaf may each have two opposite sides which in use are generally upright, and a top, the two opposite sides of the frame or the leaf each having a recess to receive a seal which extends along the corresponding side of the leaf or the frame respectively, and the top of the frame or the leaf having a generally two sided recess, drainage of water from voids between the outwardly projecting formations of the seals at the sides being via the channels of the recesses and drainage of water from voids between the outwardly projecting formations of the seal at the top being via an internal hollow of the seal, there being a plurality of openings into the internal hollow of the top seal from the voids through which water to be drained may pass.
Such a construction is particularly applicable where the sealing arrangement is for sealing a door relative to an aircraft fuselage.
According to a second aspect of the invention we provide an aircraft having a door which is sealed relative to the fuselage thereof by a sealing arrangement according to the first aspect of the invention.
According to a third aspect of the invention we provide a seal for a sealing arrangement, the seal being made of a generally resilient material and being of generally elongate configuration, the seal having at least three axially extending outwardly projecting formations and a generally plain surface which is adapted to be secured to a surface of the sealing arrangement, a first outwardly extending projection extending generally normally to the plain surface, and a pair of formations, one either side of the first formation, extending in opposite directions along a line generally parallel to the plain surface, the seal being generally tubular having a tube wall and axially extending internal hollow, the configuration of the hollow defined by the tube wall, conforming generally to the external configuration of the seal.
The invention will now be described with reference to the accompanying drawings in which: